mineral

Almandine Garnet

Almandine [Fe3Al2(SiO4)3]

Hardness: 7-7.5 (Mohs scale); Color: Deep red, brownish-red to black; Luster: Vitreous to resinous; Crystal structure: Isometric (dodecahedral); Cleavage: None (conchoidal fracture); Specific Gravity: 4.1-4.3

Hardness: 7-7
Color: Deep red, brownish-red to black
Luster: Vitreous to resinous

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily through regional metamorphism of clay-rich sedimentary rocks (shales) into schists and gneisses. It can also occur in igneous rocks like granitic pegmatites.

Uses & applications

Extensively used as an abrasive in sandblasting and water-jet cutting. High-quality transparent crystals are used in jewelry as gemstones. Also used as a geological index mineral for pressure/temperature.

Geological facts

Almandine is the most common member of the garnet group. In ancient times, it was called 'carbuncle' and was believed to light up the night for travelers and provide protection from wounds.

Field identification & locations

Identify in the field by its distinct red-to-brown color, lack of cleavage, and high hardness. It is frequently found in metamorphic schists. Common locations include New York (official state gem), Idaho, India, and Sri Lanka.